1. Field of the Invention
The present invention relates to the field of hardcopy printers which take a video input signal and reduce the video signal to a paper copy.
2. Description of the Prior Art
Hardcopy printers, used to convert a video signal into a graphic paper copy, have customarily used a CRT display which is optically focused on a recording medium such as conventional wet processed film or dry developed, photosensitive papers. A typical system for producing a telephonically transmitted image on electrostatic printing paper is shown by Byer, "Television System with a Hardcopy Printer," U.S. Pat. No. 3,422,218 where the full face image from a storage CRT is optically transmitted through a lens system onto the developing media. However, such systems are slow in that the light intensity from such a projected CRT image is relatively low and requires long exposure times.
Other prior art hardcopy printers have employed direct contact printing with a photosensitive media exploiting the use of a line of fiber optics on the face plate of a CRT wherein light from the CRT is transmitted through the fiber optic bundle to a photosensitive medium which is in direct contact with the bundle. For example, see Emmons, "Fiber Optic Cathode Ray Tube with Anti-Static discharge means," U.S. Pat. No. 3,818,131. However, such systems normally use a narrow slot or line of fiber optic bundles so that a frame is printed line by line in sequence as the paper or photosensitive media is moved across the slot of fiber optic bundles. While sufficient light intensity is obtained, printing is nevertheless slowed by exposing the photosensitive medium line by line. In addition, resolution is at best mediocre.
Full frame image printers using fiber optic face plates such as shown by Koster, "An Apparatus for Exposing Photosensitive Material," U.S. Pat. No. 3,184,753 and Kaneko et al, "Frame by Frame Video Image Recording Apparatus," U.S. Pat. No. 3,786,182 have been devised, but are as a practical matter employed only for the exposure of motion picture film inasmuch as the size of the frame, which can be simultaneously exposed in a reasonable amount of time with acceptable resolution, is confined to frame sizes normally used in conventional motion picture film. Generally, such film sizes are 35 mm or smaller which sizes are of virtually no practically usefulness as a hardcopy printer which requires at least a reasonable fraction of a conventional sheet of paper in order to provide useful hardcopy.
Therefore, what is needed is some means whereby a high speed, high resolution hardcopy printer for video signals cans be devised to produce hardcopy printout of a conventional size. What is further needed is such a multiformat, hardcopy printer which can also be programmably configured in one of a plurality of formats.